TRB 4:4 - Investigation 3 - Examining Your Fossil

Main Core Tie

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Authors

Summary

In this investigation the students will look at the fossils they made previously. They will look at the details of the fossil with a hand lens and come up with conclusions about the fossils. They will record what they see and draw conclusions about the environment of the fossil.

Background for Teachers

It is important that students learn to identify fossils by examining them with a
hand lens to look at their different characteristics. Each of the fossils they made and
discussed in Investigation Two can be examined by hand lenses.

Examining fossils helps us learn about Earths history. They help make
inferences about past life, climate, geology, and environments. Scientists are able to
construct geologic time scales when they find fossils. They are used to determine the
time period an unknown rock layer was deposited. Certain fossils have been found to
occur only in specific layers of rock. Fossils that have this characteristic are called index
fossils. When scientists find index fossils in rock layers in different locations, they are
able to establish time relationships between these areas. We know that all dinosaurs
became extinct before any saber-toothed tigers or humans appeared on Earth. We know
this because the rocks containing dinosaur remains are older than rocks with saber-toothed
tiger or human remains.

In this investigation the students will look at the fossils they made
previously. They will look at the details of the fossil with a hand lens and come
up with conclusions about the fossils. They will record what they see and draw
conclusions about the environment of the fossil.

Intended Learning Outcomes

Instructional Procedures

Pre-Assessment/Invitation to Learn

Review with the students what each fossil replica represents and how they
made each one. Discuss how nature made each of these types of fossils and how
it compares with the way they were made in class. Tell the students that they are
going to look at each fossil and make inferences of what the conditions were like
when these types of fossils were made. They can answer their questions in their
journals during their group discussions.

Instructional Procedure:

Activity One - Examining an Imprint Fossil (Impression)

Carefully take the leaf off the plaster. (It is okay if it breaks up.)

Ask the students: What do you see? (An exact impression)

Have the students look at the imprint with their hand lenses.

Ask the students: What can you see with the hand lens that you couldnt see
with just your eyes? (Very fine details of the leaf.)

Ask the student these questions:

What can you learn from this fossil? (It shows what leaves look like
even though the leaf doesnt exist anymore.)

How can this fossil tell us about the past? (It tells us what types of trees
existed in the past.)

What did the conditions have to be like for this fossil to be made? (The soil
was moist; leaves were falling off trees; the soil quickly dried up.)

If a scientist found an imprint fossil of a leaf, feather, or fish and it didnt look
like any he had seen before, what would this tell the scientist? (The organism
was now extinct.)

Activity Two - Examining the Mold and Cast Fossils (Impression)

Carefully break the two plaster parts away from each other with a hammer and
a screwdriver.

Tell the students to look at the mold, the cast, and the real shell. What do they
notice about the mold replica and the shell? (They look alike.)

Have the students look at the mold and cast fossils with their hand lenses.

Ask the students: What can you see with the hand lens that you couldnt see
with just your eyes? (Very fine details.)

Ask the student these questions:

What can you learn from this fossil? (The impression of the mold has
the same details as the real shell. The cast has the same details as the real shell.)

How can these fossils tell us about the past? (They tell us what types of shelled
animals existed in the past.)

What did the conditions have to be like for these fossils to be made? (The soil
was moist; the shell was completely covered by sediments; seeping water
dissolved the shell and left a hole in the sediments. Over the period of many
years, sediments filled the hole.)

If a scientist found mold and cast fossils of a shell and they didnt look like any
he had seen before, what would this tell the scientist? (The animal is extinct.)

Activity Three - Examining Trace Fossils

Ask the students these questions while they examine the trace fossil. Have
them write their answers in their journals.

What can you learn from this fossil? (Animals made the marks
or holes and then they left.)

How can this type of fossil tell us about the past? (It tells us what
animals' feet looked like; if they had tails; what designs their skins had,
the size of holes they dug.)

What did the conditions have to be like for this fossil to be made? (The soil
was moist; the animal had to walk on the wet soil to make an impression; it
dried in the sun with the print still there; soil had to come and cover it up to
preserve it; it was covered for many, many years.)

Why is this a fossil? (It is something that was preserved for us for many
years and we can see what animals did.)

If a scientist found a footprint and it didnt look like any he had seen before,
what would this tell the scientist? (The animal is extinct.)

Activity Four - Examining Amber (Preserved) Fossils

Ask the student questions while they examine the preserved fossil.
Have them write their answers in their journals.

With a hand lens, have the students look at the ant in the amber.

Ask the students:

What do you see? (An ant stuck in the amber.)

Is the ant all in tact (Yes.)

Why? (Because the sap preserved it. No air, water or possibly sunlight
got to it.)

How would the ant have gotten stuck in the amber? (Answers will
vary.)

What makes this type of fossil impressive? (An insect caught in sap and
the sap turning into amber will be kept all in one piece so it can be
examined.)

How can this fossil tell us about the past? (It shows us what some of the
tiny bugs looked like in the past; what bugs lived in each area; it there
were any that we don't have on Earth now.)

What did the conditions have to be like for this fossil to be made? (A
bug would have to have gotten stuck and covered by tree sap. The tree
and/or sap was buried in the ground away from the elements. The sap
fossilized into amber and preserved the bug.)

If a scientist found a bug in amber and it didn't look like any he had
seen before, what would this tell the scientist? (The bug is extinct.)

Extensions

Language Arts-

With the knowledge the students have of these types of impression fossils,
have them write a fictional essay about a fossil of their choice.

Ask the students to pick a fossil they want to write about.

Ask them to pick a type of character they want to turn into a fossil.

Ask them to write it in the form of an adventure.

The essay should have a beginning, middle, and end.

The beginning introduces the character(s), setting, and problem.

The middle tells of problems getting worse, actions taken by the character,
and decisions that have to be made.

The end tells how the fossil was formed and discovered in our day.

As students write, they need to use vocabulary words about fossils. Students
also need to use the facts they have learned about fossils. (Standard VIII, Objectives 1, 2, 3, 4, 5, 6)

Have the students read their stories in class or in groups. (Standard I, Objective 2)

Fine Arts/Visual Arts-

Have the students illustrate their stories with captions, giving a science angle to
them. (Standard III, Objective 1)

Homework & Family Connections

Have the students take home the fossil they made in school. Have them
explain to their families how they made the fossil and how it represents the way
nature makes these types of fossils.

If the students wrote stories, have them take the stories home to read to their families.

Have the students check out library books about fossils. Have them read the
books with their parents and families. Have the students tell if they come
across fossils they made in schools.

Assessment Plan

Read the students’ journals to see if they answered the questions correctly that
were asked after the examination of each fossil.

If the students wrote stories, make sure they wrote the stories using science
words and expressions about fossils, showing that they understand what they learned.